As described in published Japanese patent application no. JP-A-57-212680, a virtual machine system (VMS) generates multiple virtual machines (VM), which are logical computers, on a real computer and enables one operating system (OS) to be run for each virtual machine. In this virtual machine system, functions such as virtual machine scheduling and simulation processing of those instructions issued by a virtual machine operating system that cannot be directly executed by a real computer (hereinafter referred to simply as a "computer") are carried out by a virtual machine monitor (VMM). A virtual machine system is utilized mainly for running multiple operating systems used for different purposes on one computer. For example, both an old and a new operating system can be run on one computer by using a virtual machine system, which may occur during a transition from the old operating system to the new operating system. As another example, a virtual machine system can be used as a tool for implementing operating system tests in parallel on one computer.
Supercomputers constituted by scalar and second processors are used for high-speed scientific and technical calculations. The scalar processor activates the second processor and then performs other processing. When the second processor is activated it receives, and executes, a second job from the scalar processor. The second processor uses an interruption to communicate the termination of this second job to the scalar processor. Japanese published patent application no. JP-A-64-54542 discloses a virtual machine system in which one virtual machine (VM) has exclusive possession of a second processor (called a second unit, in the disclosure) and multiple virtual machines are able to share the scalar processor (called a scalar unit, in the disclosure).